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Abstract
Objective: Typical clinical dosimetry models for trans-arterial radioembolization (TARE) assume uniform dose distribution in each tissue compartment. We performed simple voxel-based dosimetry using post-treatment 90Y PET following TARE with 90Y-resin microspheres and investigated its prognostic value in a pilot cohort.

Method: Ten patients with 14 hepatocellular carcinoma lesions who underwent TARE with 90Y-resin microspheres were retrospectively included. The partition model-based expected target tumor dose (TDp) was calculated using a pretreatment 99mTc-macroaggregated albumin scan. From post-treatment 90Y-microsphere PET and voxel-wise S-value kernels, voxel-based dose maps were produced and the absorbed dose of each lesion (TDv) was calculated. Heterogeneity of intratumoral absorbed doses was assessed using the SD and coefficient of variation of voxel doses. The response of each lesion was determined based on contrast-enhanced MRI or CT, or both. Lesion responses were classified as local control success or failure. Prognostic values of dosimetry parameters and clinicopathological factors were evaluated in terms of progression-free survival (PFS) of each lesion.

Results: TDv was significantly different between local control success and failure groups, whereas tumor size, TDp and intratumoral dose heterogeneity were not. Univariate survival analysis identified serum aspartate transaminase level ≥40 IU/L, tumor size ≥66 mm and TDv <81 Gy as significant prognostic factors for PFS. However, only TDv was an independent predictive factor in the multivariate analysis (P = 0.022). There was a significant correlation between TDv and PFS (P = 0.009; r = 0.669).

Conclusions: In TARE, voxel-based dose index TDv can be estimated on post-treatment 90Y PET using a simple method. TDv was a more effective prognostic factor for TARE than TDp and clinicopathologic factors in this pilot study. Further studies are warranted on the role of voxel-based dose and dose distribution in TARE.

Affiliations

Min Young Yoo  1 , Jin Chul Paeng  2 , Hyo-Cheol Kim  3 , Min Sun Lee  2   4   5 , Jae Sung Lee  2   4   6 , Dong Soo Lee  2   7 , Keon Wook Kang  2   8 , Gi Jeong Cheon  2   8
1 Departments of Nuclear Medicine, Chungbuk National University Hospital, Cheongju.
2 Department of Nuclear Medicine, Seoul National University Hospital.
3 Department of Radiology, Seoul National University Hospital.
4 Interdisciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul.
5 Nuclear Emergency and Environmental Protection Division, Korea Atomic Energy Research Institute, Daejeon.
6 Department of Biomedical Sciences, Seoul National University College of Medicine.
7 Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul.
8 Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.